Index: oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation/FilteringObserver.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation/FilteringObserver.java	(nonexistent)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation/FilteringObserver.java	(working copy)
@@ -0,0 +1,105 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.jackrabbit.oak.plugins.observation;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.util.concurrent.Executor;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+import com.google.common.base.Predicate;
+
+import org.apache.jackrabbit.oak.spi.commit.BackgroundObserver;
+import org.apache.jackrabbit.oak.spi.commit.CommitContext;
+import org.apache.jackrabbit.oak.spi.commit.CommitInfo;
+import org.apache.jackrabbit.oak.spi.commit.Observer;
+import org.apache.jackrabbit.oak.spi.state.NodeState;
+
+import static org.apache.jackrabbit.oak.plugins.observation.ChangeCollectorProvider.COMMIT_CONTEXT_OBSERVATION_CHANGESET;
+
+public abstract class FilteringObserver implements Observer, Closeable {
+
+    private final static CommitInfo NOOP_CHANGE = new CommitInfo(
+            CommitInfo.OAK_UNKNOWN, CommitInfo.OAK_UNKNOWN);
+
+    private final BackgroundObserver backgroundObserver;
+
+    private final Predicate<ChangeSet> isNoop;
+
+    private NodeState lastNoop;
+
+    public FilteringObserver(Executor executor,
+                             int queueLength,
+                             Predicate<ChangeSet> isNoop) {
+        this.backgroundObserver = new BackgroundObserver(new Dispatcher(), executor, queueLength);
+        this.isNoop = isNoop;
+    }
+
+    public abstract void contentChanged(@Nonnull NodeState before,
+                                        @Nonnull NodeState after,
+                                        @Nullable CommitInfo info);
+
+    @Override
+    public final void contentChanged(@Nonnull NodeState root,
+                                     @Nullable CommitInfo info) {
+        if (isNoop.apply(getChangeSet(info))) {
+            lastNoop = root;
+            return;
+        }
+        // current change is not an noop
+        if (lastNoop != null) {
+            // report up to previous noop
+            backgroundObserver.contentChanged(lastNoop, NOOP_CHANGE);
+            lastNoop = null;
+        }
+        backgroundObserver.contentChanged(root, info);
+    }
+
+    @Override
+    public void close() {
+        backgroundObserver.close();
+    }
+
+    private static ChangeSet getChangeSet(CommitInfo info) {
+        if (info == null) {
+            return null;
+        }
+        CommitContext context = (CommitContext) info.getInfo().get(CommitContext.NAME);
+        if (context == null) {
+            return null;
+        }
+        return (ChangeSet) context.get(COMMIT_CONTEXT_OBSERVATION_CHANGESET);
+    }
+
+    private final class Dispatcher implements Observer {
+
+        private NodeState before;
+
+        @Override
+        public void contentChanged(@Nonnull NodeState root,
+                                   @Nullable CommitInfo info) {
+            if (info != NOOP_CHANGE) {
+                FilteringObserver.this.contentChanged(before, root, info);
+            }
+            before = root;
+        }
+    }
+}

Property changes on: oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/observation/FilteringObserver.java
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Added: svn:eol-style
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+native
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